The proposed research can be grouped as follows: 1) Measurement of pulmonary function, Cardiac output and Oxygen consumption following exchange transfusion with blood of low oxygen affinity in newborn premature lambs with a "Respiratory Distress" like syndrome. 2) Investigation of the effect of producing carboxyhemoglobin in fetal lambs in utero upon their tissue oxygenation as indicated by signs of fetal distress, venous 02 partial pressure, and fetal oxygen consumption.